Length-weight relationship in two marine portunid crabs, <i>Portunus (Portunus) sanguinolentus</i> (Herbst) and <i>Portunus (Portunus) pelagicus</i> (Linnaeus) from the Karnataka coast

Abstract

The carapace width/carapace length-body weight relationship in two marine Portunid crabs, Portunus (portunus) sanguinolentus and Portunus (Portunus) pelagicus from Karnataka waters was studied. Ln P.(P.) sanguinolentus, the relationships between carapace width/ carapace length and body weight were W=0.0000511 L-3.02612 and W=0.0005552 L-3.07468 for juveniles, W=0.0000362 L-3.09969 and W=0.0003974 L-3.17157 for adult males and W=0.0000658 L-2.96044 and W=0.0008287 L-2.95317 for adult females. in P. (P.) pelagicus, the relationships were W=0.00009 L-2.87333 and W=0.0004709 L-3.10602 for juveniles, W=0.0000032 L-3.61676 and W=0.0003521 L-3.178655 for adult males and W=0.0000163 L and L-3.25274 and W=0.0008874 L-2.93117 for adult females. Analysis of covariance of carapace width-weight data in these crabs suggested that between the regression equations in males and females no significant difference (P <0.05) was observed in the former species, whereas, significant difference (P <0.05) was observed between the slopes in the latter species. The present results indicated that males are heavier than females at any given length in these crabs.